If resizable is true, then the user can explicitly resize the column by
grabbing the outer edge of the column button. If resizable is true and
sizing mode of the column is #GTK_TREE_VIEW_COLUMN_AUTOSIZE, then the sizing
mode is changed to #GTK_TREE_VIEW_COLUMN_GROW_ONLY.
If resizable is true, then the user can explicitly resize the column by grabbing the outer edge of the column button. If resizable is true and sizing mode of the column is #GTK_TREE_VIEW_COLUMN_AUTOSIZE, then the sizing mode is changed to #GTK_TREE_VIEW_COLUMN_GROW_ONLY.